64 TRANSACTIONS AND PROCEEDINGS OF THE [Szss. uxrx. 
spermatia—whose destiny is unknown, although artificially 
they have been made to germinate. 
Bright red patches begin to show on the under side of 
the leaves. These are cup-like fructifications known as 
“cluster cups,” or ecidia. By the rupture of the epidermis 
the ecidiospores escape, and being carried to the leaf of a 
wheat or rye plant, germinate, giving rise to a mycelium 
which lives inside the wheat-leaf. The mycelium in the 
grass develops still another kind of spore—the uredospore. 
These, owing to their colour, give, when they break through 
the epidermis, a rusty colour to the grass. It is essential 
now to mark that these uredospores, if carried to wheat and 
other grasses, are capable of germination on these—that is, 
they are capable of giving rise to the same form of the 
disease as that which produced them. Uredospores thus 
serve to spread rapidly the disease, and they keep on being 
produced until a sudden check is brought about by the first 
signs of the approaching winter. This factor of temperature, 
with its relation to physiological drought, is interesting and 
noteworthy. Towards the end of the summer, then, the 
mycelium on the wheat, ceasing to produce uredospores, gives 
rise instead to dark thick-walled double-headed teleutospores 
in the form of which the fungus, as we have already seen, 
has the power of hibernating. 
Assuming that the weather keeps on being genial, or at 
least the winter be not so cold as in Britain, and all the other 
environmental conditions remain the same, is it not possible 
that the uredospores may continue the life-history of the 
pest on wheat and other grasses without the production of 
teleutospores and the intervention of the second and different 
host # 
The fact that in some warm countries the disease 
tlourishes in spite of the absence of the barberry plant, 
first prompted me to make a series of field observations with 
the intention of by-and-by carrying out further and more 
elaborate experiments to test the theory that in warm 
climates, if the winter be sutticiently mild, it is possible that 
the fungus can go on perpetuating itself on the wheat and 
allied grasses without the need of an intermediate host. 
During the interval ot four years the following observa- 
tions were made in wheat fields situated in various parts 
